With the exception of lufenuron, an insect growth regulator, the market for ectoparasite control in mammals has long been dominated by compositions for topical administration. The latter includes the two top-selling topical products for flea and tick control, ADVANTAGE® (imidacloprid) with efficacy against fleas (but not ticks), sold for use on dogs and cats, and FRONTLINE® (fipronil) with efficacy against fleas, ticks and scabies, also sold for use on dogs and cats. Both imidacloprid and fipronil are toxic at relatively low oral dosages. Fipronil is also known to cause emesis when given orally to control fleas, while oral efficacy of imidacloprid against targeted parasites has not been reported. Indeed, even when given topically, imidacloprid alone is reported to have little or no effect on ticks. Instead, a further active admixed with imidacloprid is required, such as the permethrin used in the ADVANTIX® product, which has some efficacy against ticks.
Although these products have efficacy against at least fleas when applied topically, the route of administration raises concerns regarding the active compounds' potentially toxic effect on humans. For both products, it is generally advised that humans not contact the administration site for several hours after application. Compliance with this advice as to treatment of domestic pets can be difficult, especially for children. In addition, the carriers used for such topical products often contain waxes, oils or other spreading agents, and so remain on the treated animal's skin for a length of time sufficient to risk environmental contamination or staining. Furthermore, certain products containing these actives include other agents that are toxic to other species. For example, permethrin is suitable for use in dogs but is potentially lethal to cats, making topical use of such products problematic in multi-species environments.
It is therefore desirable to provide an orally deliverable compound for control of targeted parasites. It is especially desirable to provide such a compound in a readily consumable dosage form.